Functional elements in the promoter region of the mouse granulocyte-macrophage colony stimulating factor (GM-CSF) gene were assessed by constructing chimeric promoters linked to the bacterial chloramphenicol acetyitransferase (CAT) gene and by employing a transient transfection assay of human T cell leukemia Jurkat cells. We previously reported that CLE2/GC-box (at positions -95 to -73, which is homologous to the NF-xB binding site) and CLE0 (at positions -54 to -40) of the mouse GM-CSF promoter are essential for transcriptional activation in response to phorbol-12-myristate-13-acetate (PMA)/calcium ionophore (A23187). Here we show that CLE2/GC-box and the NF-xB binding motif are functionally interchangeable and that CLE2/GC-box and CLE0 as a unit activate the basic GM-CSF promoter in response to PMA/calcium signals. This unit is also capable of activating heterologous promoters in response to PMA/calcium signals. In addition, we show that Tax, the trans-activator encoded by human T cell leukemia virus type I (HTLV-I), activates the GM-CSF promoter via CLE2/GC-box without the involvement of CLE0. These results indicate that PMA/A23187-dependent and Tax-dependent activation of the GM-CSF gene proceeds through distinct mechanisms.
Bibliographical noteFunding Information:
We thank Dr K. Maruyama for synthesis of ofigonucteotides, and Drs S. Miyatake, J. Fupsawa, A. Tsuboi, I. Matsuda, E. Masuda, H. J. Lee, K. Kashima, N. Nakayama, H. Masai, and M.Muramatsu for collaboration and helpful discussions. This study was supported by Schering-Plough KK and Grant-in-Aid for Scientific Research (B), no. 03454544 and Grant-in-Aid for Cancer Research, no. 04152031, The Ministry of Education, Science and Culture, Japan. The DNAX Research Institute of Molecular and Cellular Biology is supported by Schering-Plough Corporation.
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- T cell activation